基于频谱效率的低复杂度自适应MIMO系统
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摘要
在一定的误比特率(BER)下,使用自适应MQAM调制可以最大化MIMO系统的频谱效率。通过不同的算法可以得到自适应调制MIMO系统的离散速率频谱效率(DRSE)。为了进一步提高频谱效率,提出了一种基于DRSE,在不同的算法之间进行切换的低复杂度自适应机制。研究了在两种2×2信道下即:独立同分布(i.i.d)的平坦瑞利衰落信道和空间相关的瑞利衰落信道,自适应MIMO系统在正交空时块编码(OSTBC)和空间复用(SM)之间切换的自适应机制。仿真结果表明,通过选择一种最优的调制模式及发射模式的组合方式,此切换算法可以使系统的频谱效率得到有效提高,同时只增加有限的反馈信息,降低了系统复杂度。
Adaptive MQAM modulation is used to maximize spectral efficiency of MIMO systems while keeping bit error rate( BER) under a target level. Discrete rate spectral efficiency( DRSE) of adaptive modulation MIMO systems is getten by different algorithms. To enhance further the spectral efficiency,a low complexity adaptation scheme is suggested to switch across different algorithms based on the DRSE.This paper investigates the adaptation scheme that switches between orthogonal space-time block codes( OSTBC) and spatial multiplexing( SM) for MIMO systems in two types of 2 × 2 channel as flat Rayleigh fading channel without spatial correlation and spatially correlated Rayleigh fading channel.
Adaptive MQAM modulation is used to maximize spectral efficiency of MIMO systems while keeping bit error rate( BER) under a target level. Discrete rate spectral efficiency( DRSE) of adaptive modulation MIMO systems is getten by different algorithms. To enhance further the spectral efficiency,a low complexity adaptation scheme is suggested to switch across different algorithms based on the DRSE.This paper investigates the adaptation scheme that switches between orthogonal space-time block codes( OSTBC) and spatial multiplexing( SM) for MIMO systems in two types of 2 × 2 channel as flat Rayleigh fading channel without spatial correlation and spatially correlated Rayleigh fading channel.
引文
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[2]Xia P F,Zhou S L,Giannakis G B.Adaptive MIMO-OFDM based on partial channel state information[J].IEEE Trans.Signal Processing,Jan.2004,52(1):202-213.
[3]Telatar I E.Capacity of multi-antenna Gaussian channels[J].Europ.Trans.Telecom.,Dec.1999,16(8):585-595.
[4]Alamouti S M.A simple transmit diversity technique for wireless communications[J].IEEE J.Select.Areas Commun.,Oct.1998,16(8):1451-1458.
[5]Tse D,Viswanath P.Fundamentals of Wireless Communication[M].Cambridge Vniversity Press,2005.
[6]Shiu D S,Foschini G J,Gans M J,et al.Fading correlation and its effect on the capacity of multielement antenna systems[J].IEEE Trans.Commun.,Mar.2000,48(3):502-513.
[7]Catreux S,Erceg V,Gesbert D,et al.Adaptive modulation and MIMO coding for broadband wireless data networks[J].IEEE Commun.Mag.,Jun.2002,2:108-115.
[8]Forenza F,Mc Kay M R,Collings I B,et al.Switching between OSTBC and spatial multiplexing with linear receivers in spatially correlated MIMO channels[C].IEEE Proc.VTC,May 2006.
[9]Heath R W,Paulraj A J.Switching between diversity and multiplexing in MIMO systems[J].IEEE Trans.Commun.,Jun.2005,53(6):962-968.